1. Field of the Invention
The present invention relates to a television tuner and a television receiver including the television tuner.
2. Description of the Related Art
A typical known television tuner (for example, the tuner disclosed in Japanese Unexamined Patent Application Publication No. 11-298353 (FIG. 3)) is described below with reference to FIG. 2. An ultra high frequency (UHF) circuit system 21 includes an input tuned circuit 22 connected to an antenna input terminal 11, a radio frequency (RF) amplifier circuit 23 connected to the output of the input tuned circuit 22, an interstage tuned circuit 24 connected to the output of the RF amplifier circuit 23, and a mixer circuit 25 connected between the output of the interstage tuned circuit 24 and the output of an oscillating (OSC) circuit 26. A very high frequency (VHF) circuit system 31 includes an input tuned circuit 32 connected to the antenna input terminal 11, an RF amplifier circuit 33 connected to the output of the input tuned circuit 32, an interstage tuned circuit 34 connected to the output of the RF amplifier circuit 33, and a mixer circuit 35 connected between the output of the interstage tuned circuit 34 and an output of an OSC circuit 36.
A power supply voltage is supplied to the UHF circuit system 21 from a UHF supply terminal 14, while a power supply voltage is supplied to the VHF circuit system 31 from a VHF supply terminal 13.
The outputs from the mixer circuits 25 and 35 are connected to an intermediate frequency (IF) amplifier 12, and the output from the IF amplifier 12 is connected to an IF output terminal 16. A tuning voltage input into a tuning terminal 15 is supplied to the OSC circuits 26 and 36, the input tuned circuits 22 and 32, and the interstage tuned circuits 24 and 34. A desired channel is selected by the input tuned circuits 22 and 32 and the interstage tuned circuits 24 and 34, and the resulting signals are converted into IF signals in the mixer circuits 25 and 35 by local oscillation signals from the OSC circuits 26 and 36, and the IF signal is output to the IF output terminal 16.
The tuning voltage is supplied to the tuning terminal 15 from a phase-locked loop (PLL) circuit (not shown). A voltage higher than the tuning voltage is supplied to the PLL circuit from the outside of the television tuner, and the PLL circuit converts this high voltage into a tuning voltage in accordance with the channel to be selected based on the channel selection signal.
In the above-described type of television tuner, in addition to the IF output terminal 16, the tuning terminal 15, the UHF supply terminal 14, the VHF supply terminal 13, and the terminal for receiving a high voltage (not shown), many other terminals are provided, thereby making it difficult to reduce the size of the television tuner.